This invention relates to an elevator system wherein an elevator car is selectively moved and stopped to provide service to a plurality of landings within a structure and particularly to a signaling system for use therein.
Various signaling systems have been employed within elevator control systems to provide one or more command signals indicating the desire of a passenger riding within a car to stop at a particular floor or the desire of prospective passenger located at a landing to travel in either the up or down direction. Signaling systems have also been utilized within an elevator car or elsewhere to provide a remote signal indicating an emergency condition or the like.
Some signaling systems utilized within elevator systems employ heat or moisture sensitive devices which respond to the presence of a passenger in close proximity to a sensing panel to provide an output signal. Such systems, however, may be influenced by environmental conditions including temperature and humidity and thus may not provide the reliable response that can be provided through a manually operable, force actuated push button.
The use of many previous push button type elevator signaling systems has created problems because the button could be jammed or stuck in an actuated or depressed condition either accidentally or deliberately. Because many of such previous systems utilized button actuated contacts which were selectively closed in response to button actuation to complete a circuit supplying an output pulse, the jamming of the button would provide a continued output pulse to command stoppage of a plurality of elevator cars even though a previous car had serviced all existing demand at the particular landing. In addition, many elevator signaling systems employing such button actuated contacts could provide an elevator call signal thus stopping an elevator car at a landing due to a short circuit existing across the contacts which might be caused by a fire, for example, thus providing an extremely dangerous operation.
A great variety of push button switches have been constructed for various general applications. One known push button construction for general application is shown in U.S. Pat. No. 3,537,050 issued on Oct. 27, 1970 in which one or more permanent magnets are selectively connected to a magnetic core of an induction coil through an armature circuit selectively operated by a push button. Such a system provides an output pulse to render a controlled rectifier conductive whenever the armature is separated from the magnetic core of the induction coil thereby causing a collapse of the flux therein. Another type of push button actuator utilizes a transformer type solenoid circuit in which a push button operates an actuating plunger which varies the mutual inductance between primary and secondary windings with the primary winding energized by an external source and the secondary winding providing an output indicative of the relative position of the actuating rod, such as shown in U.S. Pat. No. 2,881,402 issued on Apr. 7, 1959.